Abrasive blasting equipment and self-cleaning abrasive trap therefore

ABSTRACT

Abrasive blasting equipment of the type where the tank is depressurized to stop blasting having a self-cleaning abrasive trap interposed between the tank and the exhaust valve to protect the valve from wear by abrasive entrained in the exhaust stream.

United States Pate [19 1 Dowgin ABRASIVE BLASTING EQUIPMENT ANDSELF-CLEANING ABRASIVE TRAP THEREFORE [75] Inventor: Robert V. Dowgin,Wayne, NJ.

[73] Assignee: Pauli & Griffin Co., San Fransisco,

Calif.

22 Filed: A r. 12,1971 21 Appl. No.: 133,014

{52] U.S. Cl. 51/12 [51] Int. Cl. 1324c 7/00 [58] Field of Search.....l51/8, 12

[ June 26, E973 [56] References Cited UNITED STATES PATENTS 1,899,5282/1933 Rosenberger 5l/l2 7 Primary Examiner-Donald G. KellyAttorney-Flehr, Hohbach, Test, Albritton & Herbert [S 7] ABSTRACTAbrasive blasting equipment of the type where the tank is depressurizedto stop blasting having a self-cleaning abrasive trap interposed betweenthe tank and the exhaust valve to protect the valve from wear byabrasive entrained in the exhaust stream.

5 Claims, 3 Drawing Figures Patented June 26, 1973 2 Sheets-Sheet 1NORMAL PATH ATTORNEYS Patented. June 26, 1973 2 Sheets-Sheet 2 l lll'l'll I l 1 H T w i PM mm ATTORNEYS ABRASIVE BLASTING EQUIPMENT ANDSELF-CLEANING ABRASIVE TRAP THEREFORE BACKGROUND OF THE INVENTIONOBJECTS AND SUMMARY OF THE INVENTION It is a general object of thepresent invention to provide improved abrasive blasting equipment and aselfcleaning abrasive trap therefore.

The foregoing and other objects of the invention are met by an abrasiveblasting equipment including a tank having a pressurizing inlet, aninput valve serving to selectively apply pressure to the blastingequipment and tank inlet from associated equipment, an exhaust outlet,an exhaust valve connected to said exhaust outlet adapted todepressurize the tank, an abrasive trap interposed between thetank andthe exhaust valve and .mearisconnected between the outlet side of theinput valve andthe abrasive trap so that when the inlet valve is openeda burst of air is directed backward through the abrasive trap, looseningabrasive collected in the trap and carrying the abrasive back into thetank.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is an elevational view ofabrasive blasting equipment in accordance withthe invention.

FIG. 2 is a perspective view of a self-cleaning trap in accordance withthe invention incorporated in the equipment of FIG. I. 1

FIG. 3 is a sectional elevational view of the abrasive trap shown inFIGS. 1 and 2.

DESCRIPTIONIOF THE PREFERRED EMBODIMENT Referring to the drawings, theequipment comprises a conventional tank 11 which is charged withabrasive prior to blasting. The tank is provided with a material outlet12 which may include a material metering valve 13. The tank is providedwith an inlet'l6 which is connected to high pressure air applied at 17through inlet valve 18 to pressurize the tank in a conventional man ner.The inlet 16 cooperates with a conventional popup valve connected tostandpipe in the tank 11. The high pressure air also travels along thepusher line 19 to entrain abrasive at the outlet 12.

The tank includes an exhaust outlet 21 which communicates with exhaustvalve 22. The inlet valve 18 and exhaust valve 22 may be remotelyoperated. With the inlet valve 18 closed, the exhaust. valve 22 may beopened to depressurize the tank to stop blasting. An abrasive trap 23 isinterposed between the outlet 21 and the exhaust valve 22 to protect theexhaust valve from entrained abrasive in the exhaust air. In accordancewith the present invention, a self-cleaning abrasive trap, to bedescribed below, is employed. It includes an inlet port 24 which isconnected on the downstream side of the valve 18 by a conduit 26. Everytime the valve 18 is opened to pressurize the tank, air is di rectedthrough the conduit 26 through the abrasive trap, loosening abrasive inthe trap and carrying the abrasive back into the tank. Air also flowsthrough 16 to pop-up standpipe 15 to pressurize the tank. As soon as thepressure in the tank is brought up to normal, there is little or noreverse flow through the trap.

FIG. 2 is a perspective view of a trap in accordance with the invention.The trap includes a casting 31 providing a housing which accommodates ascreening device such as screen 32. The screen isreplaced by removingthe plate 33 secured to the casting by thumb screws 34. The outlet fromthe tank is connected to the housing and communicates with the chamber36 surrounding the screen via passage 37. A baffle member 38 serves todeflect entrained abrasive whereby it does not impinge directly upon thescreen during the exhaust cycle. The exhaust air then travels inwardlythrough the screen, upwardly through the center of the screen throughpassage 39 to the exhaust valve 22, as shown by arrow 40. Conduit 26 isconnected to the port 24 of the trap 23. During the pressurizing cycle,air flows through conduit 26 downwardly into the center of the screen,outwardly through the screen, loosening all the collected abrasive andentraining the abrasive whereby it is carried back through the outletopening 37 into the tank as shown by arrow 41.

'FIG. 3 is a sectional view of the abrasive trap showing in detail thebaffle 38 and the passages 37 and 39, the screen 32 and plate 33. Thesame reference numerals as usedin FIG. 2 are applied in FIG. 3 for likeparts.

In operation of the abrasive blasting equipment, the tank is pressurizedby opening the valve 18 and closing valve 22. Simultaneously, uponopening of the valve 18, pressure is applied to the interior of the tankthrough the inlet 16 and through the exhaust outlet 21 via the trap 23which receives air along the conduit 26 which then flows through andcleans the trap. When blasting is completed, thevalve 18 is closed andvalve 22 is opened to depressurize the tank-.Any entrained abrasive inthe exhaust air impinges upon and is screened by the screen 32. It hasbeen found that not only does the self-cleaning trap eliminate or reducemaintenance down-time, but it also prevents abrasive build-up in thepop-up stems, moisture separators, pusher lines and other associatedequipment.

It is, of course, understood that the abrasive trap can be of otherconstruction. The important feature of this invention is the ability toclean the abrasive trap by the simple expedient "of providing a reverseflow of air through the abrasive collector to clean it without thenecessity of disassembly.

We claim:

1. Abrasive blasting equipment having an abrasive outlet for directingabrasive entrained in an air stream upon a surface including a tankhaving a pressure inlet, an inlet valve serving to admit air underpressure to the tank through said pressure inlet, and to said abrasiveoutlet, an exhaust outlet from said tank, an exhaust valve connected tosaid exhaust outlet to depressurize the tank, an abrasive trapinterposed between the exhaust outlet and the exhaust valve, a pop-upvalve to block reverse flow through said pressure inlet when saidexhaust valve is opened, and means for directing inlet air to said trapand said pressure inlet upon opening said inlet valve so that the airtravels backward through said trap and said exhaust outlet to clean thetrap, said inlet and exhaust valves being controlled to operate inmutually opposite open and closed conditions,

2. Abrasive blasting equipment as in claim 1 wherein said abrasive trapincludes a screen adapted to collect abrasive entrained in the exhaustair flow when said tank is exhausting.

3. Abrasive blasting equipment as in claim 1 wherein said means fordirecting inlet air to said trap comprises a conduit connected betweenthe downstream side of said inlet valve and the abrasive trap to admitinlet air under pressure to said trap whereby air travels backwardthrough said trap from the time the inlet valve is opened until thepressures in the trap and the tank are equalized.

4. Abrasive blasting equipment as in claim 2 wherein said screen iscylindrical and exhaust air flows inwardly from the outside and inletair flows outwardly from the inside.

5. Abrasive blasting equipment for use with a high pressure air sourceincluding a tank, a pressurizing path attached to said tank, an inletvalve in said pressurizing path for communication with said highpressure air source, an exhaust path attached to said tank, an exhaustvalve in said exhaust path for communication with ambient pressure, anabrasive trap between said tank and said exhaust valve, a conduitattached to the downstream side of said inlet valve in communicationwith said abrasive trap, a pop-up valve for preventing reverse flow insaid pressurizing path, and means for causing said inlet and exhaustvalves to operate in mutually opposite open and closed conditionswhereby when said exhaust valve is opened abrasive entrained in air flowthrough said exhaust path is collected in said trap and when said inletvalve is opened abrasive collected in said trap is entrained in air flowthrough said exhaust path and returned to said tank until said tank andtrap pressures equalize.

2. Abrasive blasting equipment as in claim 1 wherein said abrasive trapincludes a screen adapted to collect abrasive entrained in the exhaustair flow when said tank is exhausting.
 3. Abrasive blasting equipment asin claim 1 wherein said means for directing inlet air to said trapcomprises a conduit connected between the downstream side of said inletvalve and the abrasive trap to admit inlet air under pressure to saidtrap whereby air travels backward through said trap from the time theinlet valve is opened until the pressures in the trap aNd the tank areequalized.
 4. Abrasive blasting equipment as in claim 2 wherein saidscreen is cylindrical and exhaust air flows inwardly from the outsideand inlet air flows outwardly from the inside.
 5. Abrasive blastingequipment for use with a high pressure air source including a tank, apressurizing path attached to said tank, an inlet valve in saidpressurizing path for communication with said high pressure air source,an exhaust path attached to said tank, an exhaust valve in said exhaustpath for communication with ambient pressure, an abrasive trap betweensaid tank and said exhaust valve, a conduit attached to the downstreamside of said inlet valve in communication with said abrasive trap, apop-up valve for preventing reverse flow in said pressurizing path, andmeans for causing said inlet and exhaust valves to operate in mutuallyopposite open and closed conditions whereby when said exhaust valve isopened abrasive entrained in air flow through said exhaust path iscollected in said trap and when said inlet valve is opened abrasivecollected in said trap is entrained in air flow through said exhaustpath and returned to said tank until said tank and trap pressuresequalize.